A technique may be provided to determine, as a target breathing rhythm used to change a mental and physical state of a target person to a target mental and physical state, not only an exhalation period for exhaling and an inhalation period for inhaling, but also a grace period between the exhalation period and the inhalation period. The grace period is a switching period between the exhalation period and the inhalation period. The grace period is a period in which exhalation, or inhalation, or both exhalation and inhalation are enabled to be performed.